(S)-Pregabalin, (S)-(+)-3-(aminomethyl)-5-methylhexanoic acid, a compound having the chemical structure,
is a γ-amino butyric acid or (S)-3-isobutyl (GABA) analogue. (S)-Pregabalin has been found to activate GAD (L-glutamic acid decarboxylase). (S)-Pregabalin has a dose dependent protective effect on-seizure, and is a CNS-active compound. (S)-Pregabalin is useful in anticonvulsant therapy, due to its activation of GAD, promoting the production of GABA, one of the brain's major inhibitory neurotransmitters, which is released at 30 percent of the brains synapses. (S)-Pregabalin has analgesic, anticonvulsant, and anxiolytic activity.
Preparation of (S)-Pregabalin, as Disclosed in U.S. Pat. No. 5,616,793, and in DRUGS OF THE FUTURE, 24 (8), 862-870 (1999) is performed by obtaining the intermediate, 3-(carbamoylmethyl)-5-methylhexanoic acid (“CMH”), which is then optically resolved to give R-CMH, which is then converted to (S)-Pregabalin, as described in the following scheme:

There is a need in the art for additional processes for preparing R-CMH and salts thereof.